1. Field of the Invention
This invention relates to a jet impingement heat exchanger using a high temperature combustion gas, particularly for use in textile dyeing apparatus, and more particularly for use in dye becks used for dyeing carpets.
2. Description of Related Art
In a conventional commissioned carpet plant, a roll of carpet delivered to the plant for dyeing is unwound, twisted into a tow and looped over a power-driven reel disposed above the open top of a dye beck with the ends of the carpet being joined together to form an endless loop. A portion of the loop is submerged in the dye solution in the dye beck, and as the reel is driven, the carpet loop is continuously circulated through the dye solution. For effective dyeing, the dye solution needs to be heated to a temperature around 200.degree. F., but this temperature will vary depending on the type of yarn from which the carpet is made.
Conventionally, the dye solution in a dye beck is heated by sparging live steam generated by a boiler through the solution. This method of heating the solution, however, has certain disadvantages. For example, it entails the provision, in a carpet dyeing plant, of costly, large scale steam generation equipment. Boiler size limitations limit the number of dye becks which can be supplied with steam from a single boiler, so that in large plants it may be necessary to have multiple boilers or use a single boiler alternately to supply different banks of dye becks. Moreover, heating of the dye solution by the steam sparging method is itself somewhat slow and costly, particularly in the initial preparation of the fluid which requires considerable time and energy, and this presents another disadvantage to continuous dyeing by dye solution heated by condensed steam. Thus, it takes about 6,000 pounds of steam to raise the temperature of a typical dye solution at a rate of 3 degrees per minute. Typical steam boilers in a plant with twenty dye becks make about 50,000 pounds of steam per hour, and are coal, oil or gas fired. Due to boiler limitations, most plants only make about 50,000 pounds of steam per hour, so that a maximum of only eight dye becks of a 4,000 gallon size can be heated to raise their temperatures by 3 degrees per minute.
Still another problem in sparging arrangements is that the carpet being dyed must be protected from live steam introduced into the dye solution. This is usually accomplished by use of a perforated divider wall disposed in the dye tank. While protecting the carpet, the wall inhibits circulation which is necessary for efficient dyeing.
Other methods and apparatus for heating a dye bath in a dye beck have been previously developed. An immersed heat exchange apparatus using the flame and combustion gases from a gas or oil burner to heat the bath is shown in the patent to Hall (U.S. Pat. No. 3,289,439). The heated combustion gases flow through a ducting or tubing arrangement in a flow path which is essentially parallel to the tube walls. This heat exchanger takes up a substantial amount of space in the dye beck, and has relatively low heat transfer efficiency. Because of this, it is not well suited for use in an application where space may be limited, such as in a dye beck heating system.
It is therefore an object of the present invention to provide a heat exchanger having an efficient design requiring generally smaller heat transfer surface areas for given applications.
It is another object of the present invention to provide a heat exchanger which provides improved heating of a dye solution in a textile dye bath.
It is a further object of the present invention to provide a novel method and apparatus for heating dye solution in a textile dye bath, particularly a carpet dye beck, which is more efficient and more cost-effective than the conventional steam sparging techniques, and other heating techniques.
It is a further object of the present invention to provide two-stage heating apparatus and method which employs both submerged combustion heating technology and immersion heat exchange technology.
It is a further object of the present invention to provide a heat exchanger for use in immersion heat transfer which provides more efficient heat transfer than exchangers known in the art.
Another object of the present invention is the provision of a novel form of dye beck or like dyeing apparatus which has a self-contained dye solution heating system, so as to provide, in a plant employing a number of such dye becks, elimination of steam boilers and greater flexibility of usage than in conventional plants where plural dye becks are supplied with steam from multiple boilers or a large common boiler.